1. Technical Field
The present invention relates to a signal receiving device and signal receiving method to generate and demodulate an IF (Intermediate Frequency) signal by combining a receiving RF (radio frequency) signal and a local oscillating signal.
2. Description of Related Art
Conventionally a signal receiving device is known wherein an IF filtering circuit is equipped to receive an RF signal, and generate an IF signal of an intermediate frequency by mixing the RF signal and a local oscillating signal so as to filter the IF signal. As an IF filtering circuit, generally an active filter is used wherein a resistance and a condenser are set as a filter constant. A resistance value and a capacity value of a condenser are optimized according to a format of an RF signal to receive, an IF frequency, a passing bandwidth, an out-of-band attenuation, or the like.
For example, in order to able to receive a plurality of RF signals having different bandwidths required with a signal receiving device, a method is known wherein the signal receiving device is installed with a plurality of IF filtering circuits so as to select an optimal IF filtering circuit for an RF signal to receive (Patent Literature 1).
Patent Literature 1: Japanese Patent Kokai No. 2002-217768